DE102017204746B4 - HYDROGEN GAS STATION - Google Patents

Abstract

An apparatus (1) for providing a compressed gas (H) comprises at least a first container (11) in which a gas (H) to be dispensed is stored at a first pressure, and preferably at least one second container (21, 31) the gas to be dispensed (H) is stored at a second, higher pressure. The device comprises a hydraulic system for pumping a fluid (F) into the corresponding container (11, 21, 31) when the gas (H) is dispensed, so that a pressure drop in the respective container (11, 21, 31) is prevented the pressure in the respective container is kept constant. The fluid comes into direct contact with the gas (H). In particular, the invention finds application in a hydrogen refueling station for refueling a vehicle with gaseous hydrogen.

Description

The present invention relates to a device for providing a compressed gas and a corresponding method for providing a compressed gas. Such a device can be used in particular in an arrangement for filling a tank with a compressed gas, in particular a vehicle tank with a gaseous fuel, preferably in a hydrogen filling station for refueling a vehicle tank with gaseous hydrogen.

In addition to conventional internal combustion engines as a drive for vehicles, especially motor vehicles, alternative drives gain in importance. These include, for example, fuel cell drives. These require for their operation hydrogen (H ₂ ), which is provided either in liquid form ("liquid" LH ₂ , usually at about -253 ° C)) or in compressed gaseous form (GH ₂ ). For example, the hydrogen in a vehicle may be stored in a cryotank in liquid form. However, due to disadvantages of liquid storage, in particular the permanent loss due to outgassing, storage of the hydrogen in gaseous form in a vehicle tank is increasingly preferred, more preferably at a (minimum) pressure of 70 MPa (700 bar) or at 35 MPa.

For refueling such vehicles hydrogen refueling stations are provided which, like conventional refueling stations, have a refueling device with a filler neck for coupling to the vehicle tank and make it possible to refuel the vehicle tank in a few minutes. Usually, the hydrogen filling station is supplied with hydrogen in liquid form. For fueling a vehicle, the hydrogen is vaporized, compressed and stored in high-pressure tanks. Since the pressure in the high-pressure tanks drops when filling the vehicle tank, a compressor is necessary, which compresses the hydrogen. The compressor has to do all the more work the more the pressure in the high-pressure tanks falls during the refueling process. The compressed hydrogen is then cooled down, for example to about -40 ° C, and then supplied to the vehicle tank.

Disadvantages of this solution are in particular the high installation, operating and maintenance costs of a compressor. In addition, the operation of a compressor is maintenance-intensive and may be prone to disturbances that interrupt the operation of the hydrogen refueling station.

The object of the invention is therefore to provide a device for providing a compressed gas that is simple, inexpensive, and reliable. Furthermore, a corresponding method for providing a compressed gas is to be provided. In particular, the device may be at least part of a device for filling a container with a compressed gas, in particular a vehicle tank with a gaseous fuel.

The object is achieved by a device and a method having the features of the independent claims. Preferred embodiments and further developments are specified in the dependent claims.

According to the invention, a device for providing a compressed gas comprises at least a first container, which is filled with a gas to be dispensed with a first pressure. In addition, the device comprises a hydraulic system with a fluid that is configured to prevent a pressure drop in the first container below the first pressure. This is done by pumping the fluid into the first container, the fluid coming into direct contact with the gas to be dispensed in the first container. According to the invention, the pressure in the first container is kept substantially constant.

In addition, the device further comprises at least a second container, which is filled with the gas to be dispensed with a second pressure, wherein the second pressure is higher than the first pressure. In particular, the device is adapted to first output the gas from the first container and then the gas from the second container into the tank to be filled. In addition, the hydraulic system is further arranged to prevent, in the same manner as in the first container, a pressure drop in the second container below the second pressure, i. the fluid is pumped into the container so that it comes in direct contact with the gas. According to the invention, the pressure is kept substantially constant even in the second container.

A corresponding method for providing a compressed gas comprises discharging the gas from the first container, which is filled with the gas to be dispensed with the first pressure, wherein a pressure drop in the first container under the first pressure is prevented by a fluid in the first Container is pumped so that it comes into direct contact with the gas to be dispensed in the first container. According to the invention, the pressure in the first container is kept substantially constant.

In addition, the method further comprises dispensing the gas from a second container, which with the gas to be dispensed with a second pressure is higher than the first pressure, wherein a pressure drop in the second container is prevented under the second pressure by a fluid is pumped into the second container, so that it is in direct contact with the gas to be dispensed in the second Container is coming. Specifically, the gas is discharged from the second container after the gas is discharged from the first container. According to the invention, the pressure is kept substantially constant even in the second container.

The device may in particular be at least part of an arrangement for filling a tank with a compressed gas. In particular, it may be a device for refueling a vehicle tank with a gaseous fuel, preferably a hydrogen refueling station for refueling a vehicle tank with gaseous hydrogen. In other words, the apparatus can be advantageously used in an arrangement for filling a tank with a compressed gas, such as a hydrogen filling station. A device for filling a tank with a compressed gas, such as a hydrogen filling station, comprises a refueling device for delivering the compressed gas to the tank to be filled.

The invention provides a device or a corresponding method for the simple, cost-effective and reliable refueling of a vehicle tank with a compressed gaseous fuel. By avoiding the pressure drop in the containers in which the gas is stored, the gas to be dispensed is kept ready at any time with a sufficiently high pressure in the containers, for example to fill a vehicle tank.

Since the avoidance of the pressure drop or the pressure is kept constant by pumping the fluid into the corresponding container, the device is less susceptible to interference and less maintenance-intensive than, for example, a device with a mechanical cylinder-piston assembly. Direct contact of the fluid with the gas to be dispensed means that the fluid is pumped directly into the container, without being separated from the gas to be dispensed, for example, by a piston. By this structure, additional moving parts, such as a piston, avoided, which requires maintenance and wear, for example, due to the necessary sealing. In addition, due to the direct contact of the fluid with the gas, possibly resulting heat can be dissipated effectively via the fluid.

As just described, the prevention of the pressure drop or the keeping constant of the pressure in the container or the container of the device by means of a fluid, which is pumped into the respective container takes place. The fluid is pumped into the respective container to a corresponding extent as the gas is discharged from the respective container in order to keep the pressure in the respective container constant. According to the invention, the pressure in the respective container is kept substantially constant, i. There is no compression of the gas by pumping the fluid into the respective container. In this case, the device will work without a compressor.

In particular, the hydraulic system may include at least one reservoir for the fluid. It should be understood that the hydraulic system may further include corresponding pumps, conduits, and valves that permit delivery of the fluid to the respective container. The components of the hydraulic system, such as the hydraulic pumps, are much cheaper and simpler in construction than a compressor. In addition, the operation of a system without a compressor is more reliable than the operation of a compressor system.

After the gas has been substantially completely dispensed from one of the containers or the volume of the gas falls below a predetermined minimum volume, the fluid, which now occupies substantially the entire volume of the container, may be returned from the corresponding container for reuse in the store or, if appropriate be further pumped into the following container. For this purpose, valves on the containers can be set up to switch over when the container is empty or filled with fluid. It may be an automatic switching of the valves, for example, triggered by a volume, weight or level measurement of the fluid or gas, either from inside or outside the container, for example by means of a suitable sensor which detects the gas or the fluid.

Preferably, the fluid is an ionic fluid. An ionic fluid has the advantage that it does not react with the gaseous fuel. Ionic fluid that has mixed with the gaseous fuel may simply be separated by means of a separator prior to dispensing into the vehicle tank and returned to the hydraulic circuit. Similarly, instead of an ionic fluid, a fluid having low gas solubility, ie, a fluid that does not or poorly dissolves in the gas to be dispensed, can be used to ensure that the gas to be dispensed is substantially free of the fluid and high in purity having. General and regardless of the type of fluid, it is advantageous if a separator is provided which separates fluid mixed with the gas to be dispensed before the gas is discharged to a vehicle. The fluid can then be recycled back into the hydraulic circuit. A separator is particularly advantageous because the fluid comes in direct contact with the gas to be dispensed, whereby a part of the fluid can mix with the gas.

Preferably, the highest pressure in the containers, for example the second pressure in the second container, is greater than or equal to a target pressure to be reached in a tank to be filled. As explained above, a pressure of at least 70 MPa in the vehicle tank is preferred. The second pressure is therefore preferably 70 MPa or more, especially up to 100 MPa, for example about 80 MPa.

If a plurality of containers are provided, the order of the containers from which the gas is dispensed is advantageously predetermined. Specifically, gas is first discharged from a container at a lower pressure, then gas from a container at a higher pressure. In this way, a vehicle tank can be refueled successively from tanks with increasing pressure. In the initially empty or at least partially filled vehicle tank, there is a low pressure, so that refueling can be started with a low pressure. As soon as a pressure equalization between the vehicle tank and the corresponding container takes place, the container is switched to the next higher pressure level.

By this cascaded storage of the gas to be dispensed, i. The storage of the gas in containers with different pressures and the sequential discharge of the gas with increasing pressure, energy can be saved, since the provision of a high pressure principle requires a lot of energy. However, a high pressure in the containers is not necessary at the beginning of a dispensing operation (for example vehicle refueling when the vehicle tank is under a low pressure), but only with increasing filling of the vehicle tank. In addition, costs can be saved, since containers for lower pressure are cheaper than high-pressure vessels.

It is understood that the method for refueling a vehicle does not have to be started with the container with the lowest pressure level. In particular, if the vehicle tank is still partially filled and corresponding pressure in the vehicle tank, refueling is started with that container in which, compared to the other containers, the smallest pressure prevails that is greater than the pressure in the tank to be filled. For this purpose, the pressure prevailing in the vehicle tank pressure is determined, for example by means of a test shock at the beginning of the refueling process, so that the corresponding container can be determined, with which the refueling process is started.

In an advantageous embodiment, the device comprises at least a third container, which is filled with the gas to be dispensed with a third pressure. That is, preferably, the gas to be dispensed is kept at three different pressure levels and discharged sequentially with increasing pressure. Also in the third container is advantageous, as already explained in connection with the first and second container, a pressure drop avoided by pumping the fluid into the third container. It is understood that more than three containers, for example four or five containers, may be provided, the containers being respectively filled with a different pressure rising from the first to the last container and discharging the gas from the corresponding container as explained above is kept constant or a pressure drop is avoided.

• 1 zeigt schematisch den Aufbau einer Wasserstofftankstelle gemäß der vorliegenden Erfindung.
• 2a und 2b zeigen Beispiele von Behälteranordnungen einer Wasserstofftankstelle.
• 3 zeigt ein Diagramm der Behälter einer Wasserstofftankstelle.

The invention will be described below with reference to the accompanying drawings. The drawings are merely schematic illustrations for explaining the invention. It is understood that the invention is not limited to the illustrated specific embodiments.

• 1 schematically shows the structure of a hydrogen filling station according to the present invention.
• 2a and 2 B show examples of tank arrangements of a hydrogen filling station.
• 3 shows a diagram of the containers of a hydrogen filling station.

Referring to 1 becomes a device 1 for filling a vehicle tank 101 of a vehicle 100 with gaseous fuel using the example of a hydrogen filling station according to the present invention. The term vehicle is understood to mean any vehicle which can be driven by means of a gaseous fuel drive, in particular motor vehicles such as cars, buses or trucks, but also other commercial vehicles, watercraft, ships, etc. The gaseous propellant is preferably gaseous hydrogen. Therefore, the following description refers to refueling a vehicle with gaseous hydrogen. In particular, a vehicle is a fuel cell vehicle. Optionally, the device 1 also serve to provide other compressed gases, such as other gaseous fuels, such as natural gas (CNG, " Compressed Natural Gas "), or other industrial gases such as nitrogen, oxygen, argon, helium, etc.

A hydrogen filling station comprises a device 1 according to the present invention, in particular one or more containers 11 . 21 . 31 which are filled with compressed gaseous hydrogen, as described below with reference to 3 will be explained in more detail. In particular, the device can 1 replace a supply (eg a pre-supply or delivery tank), a compressor and high-pressure tanks of a standard hydrogen filling station. Furthermore, the hydrogen refueling station includes a station 50 with a cooling unit 51 to cool the hydrogen when refueling a vehicle down to -40 ° C, and a refueling device 52 which usually has a filler neck or a PTO coupling for coupling to the vehicle tank 101 as well as a measuring and payment system and an operating unit. These components are known in the art and are therefore not explained in detail. Usually, the cooling unit form 51 and the refueling device 52 the stationary part of a hydrogen filling station while the containers 11 . 21 . 31 are mobile. In particular, the containers 11 . 21 . 31 advantageously filled in a central location and empty containers are replaced at the hydrogen filling station against full containers. However, it is also possible to fill up the containers on site.

2a and 2 B show various examples of tank or tank arrangements for a hydrogen filling station. As in 2a As shown, the containers can be mounted on a truck semi-trailer 2 be arranged. The containers 11 . 21 . 31 can be divided into different units, groups or sections that contain hydrogen of different pressures. A unit of containers may comprise one or more containers.

Alternatively, as in 2 B shown, the containers can 11 in smaller units, for example in containers 3 be bundled. In this way, the scalability is improved, as it also smaller hydrogen refueling stations can be provided, for example, if the space at the installation is limited or the need and utilization of the hydrogen filling station is lower. This is particularly advantageous in the early stages of the deployment of hydrogen refueling stations and corresponding hydrogen powered vehicles. Like the containers on a truck semi-trailer, the containers of a bundle may be subdivided into units of different pressure. Alternatively, all containers of one bundle of hydrogen may be filled with the same pressure, and optionally two or more bundles of containers, each with different pressure levels, may be provided.

The following statements refer to both in 2a as well as the in 2 B shown exemplary arrangements of containers. It is understood that other arrangements, sizes and numbers of containers can be used within the scope of the invention. For example, containers of different sizes can also be used. Advantageously, containers of a unit are arranged adjacent to one another and the units are sorted according to ascending pressure. This simplifies the control and the cable run. However, the containers need not be sorted according to the filling pressure, as long as the driving of the desired container is ensured.

In 3 is a diagram of the containers 11 . 21 . 31 a hydrogen filling station according to the present invention. In the illustrated embodiment, there are three units 10 . 20 . 30 of containers with by way of example three containers 11 . 21 . 31 shown. It is understood that a hydrogen refueling station instead of the three illustrated containers 11 . 21 . 31 per unit may have only one or two containers or more than three containers, which are each filled with the same pressure. Likewise, the device may have only one unit of containers, two units of containers or more than three units, for example four or five units.

Preferably, containers with three pressure levels, ie three units 10 . 20 . 30 provided by containers. The pressure increases from unit to unit, starting at a low pressure of the first unit 10 of containers 11 (for example 25 to 50 MPa), over a mean pressure of the second unit 20 of containers 21 (For example 40 to 70 MPa) until the pressure in the third and last unit 30 of containers 31 at least the target pressure to be achieved in the vehicle tank 101 corresponds to (for example 70 to 90 MPa). The target pressure to be achieved in the vehicle tank 101 is preferably at least 70 MPa. These values are exemplary only and vary depending on the application. For example, the target pressure to be achieved may be as low as about 35 MPa and the pressure in the containers 11 . 21 . 31 be correspondingly lower.

In a fueling process is hydrogen H initially from a container 11 the first unit 10 spent until the pressure between the container 11 the first unit 10 and the vehicle tank 101 is balanced. In the further course of the refueling process, the vehicle tank 101 then up to the pressure of the second unit 20 of containers 21 and finally to the target pressure by means of the third unit 30 of containers 31 filled. It can first be done a test shock to tightness of the system and tank parameters, such as the level or filling pressure in the vehicle tank 101 , and then determine the refueling process optionally with a container of the second unit 20 or third unit 30 to start. This cascading arrangement of the containers 11 . 21 . 31 with different pressure levels can contribute to the energy savings as already explained. Instead, the device can 1 however, only one container or unit of containers having a pressure greater than or equal to the target pressure to be reached in the vehicle tank.

When emitting the hydrogen H from one of the containers 11 . 21 . 31 the volume of the container will be commensurate with a fluid F filled up like the hydrogen H is output to keep the pressure in the respective container constant. This is done by pumping the fluid F in the respective container 11 . 21 . 31 by means of a hydraulic pump 41 achieved, in particular from a memory 40 , The fluid F is thereby directly into the respective container 11 . 21 . 31 pumped so that it is in contact with the hydrogen H comes, ie without separation between the hydrogen H and the fluid F , Every container 11 . 21 . 31 becomes independent of the other containers 11 . 21 . 31 controlled.

After the hydrogen H has been completely dispensed from a container and the container accordingly substantially completely with the fluid F is filled, the refueling operation is continued with the next container, either with a container of the same pressure level or with a container of the next higher pressure level. The fluid F gets out of a container 11 . 21 . 31 back into the store or further pumped into the next container, from which the hydrogen H is issued. This will continue until the hydrogen H from all containers 11 . 21 . 31 was removed. The fluid F which is hydrogen H saturated, remains in the containers 11 . 21 . 31 , so no emission of hydrogen H takes place in the atmosphere. With the fluid F it may in particular be an ionic fluid or any fluid with low gas solubility.

Before the hydrogen H to the station 50 , in particular the refueling device 52 for refueling the vehicle tank 101 is sent, possibly with the hydrogen H mixed fluid F by means of a separator 44 from the hydrogen H removed and back to the store 40 guided. The fluid F and the hydrogen H can mix as the fluid F in the containers 11 . 21 . 31 in direct contact with the hydrogen H comes. The hydrogen H is then cooled down and then filled via a filler neck in the vehicle tank. The refueling operation is advantageously carried out in accordance with the requirements of the SAE J2601 standard.

The containers 11 . 21 . 31 For example, via 3/3-way valves 42 may be connected to the line of the hydraulic system to the respective hydraulic line to the containers 11 . 21 . 31 shut off, supplying the ionic fluid F to the containers 11 . 21 . 31 and returning the fluid F in the store 40 to allow. As mentioned, if appropriate, it may also be provided that the fluids F from a container (by means of the pump 41 ) to a subsequent container. Furthermore, simple shut-off valves 43 provided to the expulsion of the hydrogen H from a container 11 . 21 . 31 to start or stop or interrupt. The valves 42 . 43 for the fluid F or for the hydrogen H can like in 3 indicated on opposite sides of the container 11 . 21 . 31 be arranged. It is understood, however, that other valves and other valve arrangements can be provided which a correspondingly desired activation of the individual containers, ie supply and discharge of the fluid F on the one hand and removal of hydrogen H on the other hand, allow. It may also be two or more containers connected to each other and controlled by a common valve. This can save costs for the valves. However, then more fluid is needed because then several containers are filled at the same time.

If the containers 11 . 21 . 31 as in 2a shown on a truck semi-trailer 2 are arranged, it is advantageous, although the hydraulic pump 41 and the memory 40 for the ionic fluid F on the trailer 2 are arranged. Then the trailer needs 2 at the station 50 just connected to electricity and the hydrogen line connected. If the hydraulic pump 41 and the memory 40 for the fluid F in the station, the hydraulics must also be connected. When using electrical components, especially in the hydraulic pump 41 and the valves 42 . 43 , pay attention to explosion-proof equipment. Alternatively, these components can also be driven pneumatically.

It is also conceivable that the entire hydrogen filling station, including the cooling unit and the refueling device, is arranged on the truck semi-trailer. This increases the flexibility and mobility of the entire hydrogen filling station.

As explained above, the containers can also be as in 2 B be bundled in smaller units and in individual containers 3 are arranged. Here, the hydraulic pump 41 , the valves 42 . 43 as well as the memory 40 be arranged with the fluid F in the respective unit.

By using a fluid, which is pumped into the container as described, when the hydrogen is dispensed during a refueling operation, can be dispensed with an otherwise usual in a hydrogen refueling compressor. By cascading containers of different pressure levels, the efficiency can be further improved.

Claims (10)

Apparatus (1) for providing a compressed gas (H), comprising: a refueling device (52) for delivering the compressed gas (H) to a tank (101) to be filled, at least one first container (11) which is filled with the compressed gas (H) with a first pressure, - At least a second container (21, 31) which is filled with the compressed gas (H) with a second pressure, wherein the second pressure is higher than the first pressure, and - A hydraulic system with a fluid (F), wherein the hydraulic system with the first container (11) and the second container (21, 31) is connected to supply the fluid (F) to the first container (11) or to the second container (21, 31) and wherein the hydraulic system is adapted to pump the fluid (F) into the first container (11) as the compressed gas (H) discharged from the first container (11) and by means of the refueling device (52) is delivered to the tank (101) to be filled in order to keep the pressure in the first container (11) constant, the fluid (F) being in direct contact with the gas (H) to be dispensed in the first container (11 ) comes, and wherein the hydraulic system is further configured to pump the fluid (F) into the second container (21, 31), as the compressed gas (H) from the second container (21, 31) bunged and by means of the refueling device (52) to the filling tank (101) is delivered to keep the pressure in the second container (21, 31) constant, wherein the fluid (F) comes into direct contact with the gas to be dispensed (H) in the second container (21, 31) , Device after Claim 1 wherein the second pressure is at least 35 MPa or at least 70 MPa, preferably 80 MPa. Device after Claim 1 or 2 further comprising a separator (44) arranged to mix fluid (F) mixed with the gas (H) after discharging the gas (H) from the first container (11) and optionally the second container (21, 31) deposit. Device according to one of Claims 1 to 3 wherein the fluid (F) is an ionic fluid. Method for providing a compressed gas (H), comprising the steps: Providing a first container (11) which is filled with the compressed gas (H) with a first pressure, Providing at least one second container (21, 31) which is filled with the compressed gas (H) with a second pressure, the second pressure being higher than the first pressure, - Providing a hydraulic system with a fluid (F), wherein the hydraulic system with the first container (11) and the second container (21, 31) is connected or connected to supply the fluid (F) to the first container (11 ) or the second container (21, 31), - Outputting the compressed gas (H) from the first container (11) and by means of a refueling device (52) delivering the compressed gas (H) into a tank to be filled (101), wherein the pressure in the first container (11) kept constant is pumped by the fluid (F) in the first container (11), as the compressed gas (H) from the first container (11) and delivered by the refueling means (52) to the tank to be filled (101) wherein the fluid (F) comes into direct contact with the gas (H) to be dispensed in the first container (11), and after discharging the compressed gas (H) from the first container (11), discharging the compressed gas (H) from the at least one second container (21, 31) and by means of the refueling means (52) delivering the compressed gas (H) into the tank (101) to be filled, wherein the pressure in the second tank (21, 31) is kept constant by pumping the fluid (F) into the second tank (21), like the compressed gas (H) from the tank second container (21, 31) and delivered by the refueling means (52) to the tank to be filled (101), wherein the fluid (F) in direct contact with the gas to be dispensed (H) in the second container (21, 31 ) comes. Method according to Claim 5 wherein the compressed gas (H) is discharged from the first container (11) and delivered to the tank (101) to be filled by the refueling means (52) until a pressure difference exists between the first container (11) and the tank to be filled (101) is balanced. Method according to Claim 5 or 6 wherein the compressed gas (H) from the second container (21, 31) as long as and delivered by the refueling means (52) to the tank to be filled (101) until a pressure difference between the second container (21, 31) and the tank (101) to be filled is balanced or until a target pressure to be reached in the tank (101) to be filled is reached. Method according to one of Claims 5 to 7 wherein the compressed gas (H) is discharged from the second container (21, 31) after the compressed gas (H) is completely discharged from the first container (11) and the first container (11) is completely filled with the fluid (F ) is filled. Method according to one of Claims 5 to 8th wherein the second pressure is greater than or equal to a target pressure to be reached in the tank (101) to be filled, and / or wherein the second pressure is at least 35 MPa or at least 70 MPa, preferably 80 MPa. Method according to one of Claims 5 to 9 wherein the compressed gas (H) after being discharged from the first container (11) and the second container (21, 31) is passed through a separator (44) to separate fluid (F) mixed with the gas (H).

Images